The calculation of the Hybrid MultiFractal Musgrave texture was revised to address two issues: I) texture discontinuities occurring when Detail was a non integer greater than 2 and; II) levels of detail in the interval [0,1) repeating the levels of detail in the interval [1,2).

Notes:

• the Musgrave calculation currently appears repeated in 4 files (that I could find) and 4 times in each file (for 1D,2D,3D,4D cases), so this patch repeats the same fix in 16 locations.
• From my tests, this patch corrects the Hybrid MultiFractal Musgrave texture in 4 situations: 1) when viewed with Eevee; 2) when viewed with Cycles; 3) when viewed with Cycles with OSL; 4) when generated with Geometry Nodes. I've attached a blend file covering these 4 situations. It is possible there is another use of Musgrave I forgot to consider.

Files:
Current Musgrave behavior: